Magnetic resonance imaging apparatus

ABSTRACT

The MRI apparatus includes a housing that includes a bore; a table which is configured to be moved into the bore; and a beam projector that is configured to be disposed on the table, and to project an image into the bore. The beam projector includes a coil which is configured to be disposed so that a central axis of the coil is parallel to a center axis of the bore.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of U.S. application Ser. No.14/491,148 filed Sep. 19, 2014, which claims priority from Korean PatentApplication No. 10-2013-0114139, filed Sep. 25, 2013, in the KoreanIntellectual Property Office, the disclosures of which are incorporatedherein in its entireties by reference.

BACKGROUND

1. Field

One or more exemplary embodiments relate to a magnetic resonance imaging(MRI) apparatus, and more particularly, to an MRI apparatus fordisplaying an image in a bore.

2. Description of the Related Art

MRI apparatuses are used for medical diagnostic imaging. MRI apparatusesinclude a main magnet that generates a main magnetic field, gradientcoils that generate magnetic field gradients to select slices andprovide positional information, and a radio frequency (RF) coil that isused to apply an electromagnetic wave to the human body for resonatingan internal magnetization vector of the human body, and to receive amagnetic resonance (MR) signal. The main magnet and the coils which areused to capture an MR image are accommodated in a housing, which has agenerally cylindrical structure having a bore in which a patient isplaced during MR imaging.

The bore of an MRI apparatus is a small constrained space and may givethe object a closed in feeling. Thus, when the capturing of the MR imageis performed, there is a high possibility that the object would move dueto boredom or discomfort which may result in a reduced quality of animage and the MRI would need to be re-executed. To this end, proposed isa system that provides image information to an object being imaged. Asone example, proposed is a method in which an object wears glassesdisplaying an image, or looks at an image displayed outside of thehousing by using a mirror provided in the bore. However, a method usingglasses causes inconvenience to an object because the glasses displayingan image may enhance a closed in feeling, and a method using a mirrordegrades a quality of a provided image.

SUMMARY

Exemplary embodiments may address at least the above problems and/ordisadvantages and other disadvantages not described above. However,exemplary embodiments are not required to overcome the disadvantagesdescribed above, and may not overcome any of the problems describedabove.

One or more exemplary embodiments include an MRI apparatus that displaysan image in a bore to mitigate inconvenience of an object caused bylong-time image capturing and a narrow space in which the object islocated. Furthermore, the inventor found a problem in which when a beamprojector for displaying an image in a bore is disposed in the bore,noise of an audible frequency band occurs in the beam projector.Therefore, provided is an MRI apparatus for preventing the noise fromoccurring.

According to one or more exemplary embodiments, a magnetic resonanceimaging (MRI) apparatus includes: a housing that includes a bore inwhich a magnetic field for capturing a magnetic resonance (MR) image isapplied; a beam projector that is disposed in the bore of the housingduring capture of the MR image, and projects an image onto an inner wallincluded in the bore of the housing; and a controller that controls thebeam projector, and transfers a video signal to the beam projector,wherein, the beam projector includes at least one coil, and the beamprojector is disposed such that a direction of a magnetic field, whichis generated with a current applied to the at least one coil, isparallel to a direction of the magnetic field which is applied forcapturing the MR image in the bore.

The magnetic field in the bore may be a main magnetic field thatmagnetizes an atomic nucleus of a chemical element causing an MRphenomenon.

The at least one coil may have an air-core coil structure.

The at least one coil may be a cylindrical coil, and the at least onecoil may be disposed such that a central axis of the cylindrical coil isparallel to a direction of the magnetic field which is applied forcapturing the MR image in the bore.

The beam projector may include: an image panel that displays an image; alight source that irradiates light onto the image panel; a light sourcedriver that supplies certain power to the light source; and a projectionlens that projects the image displayed by the image panel, and the atleast one coil may be an inductor provided at the light source driver.

The light source driver may include a DC converter that converts inputpower into a predetermined voltage.

The light source may include red, green, and blue light sources, and thelight source driver may sequentially supply a current to the red, green,and blue light sources.

The MRI apparatus may further include a moving table on which an objectis located, and which enters the bore of the housing, wherein animage-forming position of the inner wall of the housing, in which theimage projected from the beam projector is formed, may be movedaccording to a position in which the moving table enters an inside ofthe bore of the housing.

The beam projector may be disposed on the moving table.

The beam projector may be disposed near at least one of both ends in alength direction of the moving table.

The MRI apparatus may further include a detachable module that isdisposed on the moving table, and is detachably attached to the beamprojector.

A detachable module which is detachably attached to the beam projectormay be disposed on the moving table. The detachable module may includefirst and second detachable modules which are respectively disposed nearboth ends in a length direction of the moving table. The detachablemodule may transfer power and a video signal, which are input from thecontroller, to the beam projector. Each of the first and seconddetachable modules may include a detachable sensor that detects thepresence of attachment/detachment of the beam projector. The controllermay supply power and the video signal to only one of the first andsecond detachable modules, to which the beam projector is attached,according to information about the presence of attachment/detachment ofthe beam projector.

The detachable module may include a projection direction changing unitthat changes an image projection direction of the beam projector.

The detachable module may include an optical engine module, whichprojects an image, and a projection direction changing unit that changesan image projection direction of the optical engine module.

The beam projector may include a luminance sensor, and beam brightnessof the beam projector may be controlled according to an internalluminance state of the bore.

The beam projector may include a driving module that provides drivingforce to the projection direction changing unit in order for the imageprojection direction of the beam projector to be changed, and thecontroller may control the driving module according to manipulation of auser in order for the image projection direction of the beam projectorto move along a posture or looking direction of the object.

The beam projector may include a driving module, which provides drivingforce to the projection direction changing unit in order for the imageprojection direction of the beam projector to be changed, and a positiontracing sensor that traces the posture or looking direction of theobject. The controller may control the driving module in order for theimage projection direction of the beam projector to move along theposture or looking direction of the object detected by the positiontracing sensor.

The beam projector may include a luminance sensor, and beam brightnessof the beam projector may be controlled according to an internalluminance state of the bore.

The projected image may include at least one of an MR image beingcaptured, imaging information, and video content.

The inner wall of the housing may include a cylindrically curvedsurface.

The cylindrical structure may denote a case, in which the bore of thehousing is wholly cylindrical, or a case in which the bore of thehousing is partially cylindrical. Alternatively, at least one surface ofthe inner wall of the housing may be flat, and the beam projector mayproject an image onto the at least one flat surface.

The MRI apparatus may include a correction processing unit that causesfirst distortion in an image to be projected by the beam projector, andprocesses a signal of the image to be projected by the beam projector soas to counteract second distortion of an image to be generated accordingto a curved shape of the inner wall of the housing or askew imageprojection. The second distortion may be curved-surface distortioncaused by the curved shape of the inner wall of the housing or skewdistortion caused by askew projection. The first distortion may bepre-distortion because the first distortion is previously caused tocounteract the curved-surface distortion or the skew distortion. Thecorrection processing unit may change a distortion amount of the firstdistortion according to the image projection direction of the beamprojector being changed.

The beam projector may further include a heat dissipating module thatdissipates generated heat. The heat dissipating module may be a heatsink of a nonmagnetic material.

According to one or more exemplary embodiments, a method of displayingan image in a bore of a magnetic resonance imaging (MRI) apparatusincludes: entering a moving table, on which an object is located, into abore of a housing in which a magnetic field for capturing a magneticresonance (MR) image is applied; disposing a beam projector in the boreof the housing; and projecting an image onto an inner wall included inthe bore of the housing, wherein, the beam projector includes at leastone coil, and the disposing of a beam projector includes disposing thebeam projector such that a direction of a magnetic field, which isgenerated with a current applied to the at least one coil, is parallelto a direction of the magnetic field which is applied for capturing theMR image in the bore.

The method may further include causing first distortion in an image tobe projected by the beam projector, and counteracting second distortionof an image to be generated according to a curved shape of the innerwall of the housing or askew image projection.

The method may further include: changing an image projection directionof the beam projector which is projected onto the inner wall of thehousing; and changing a distortion amount of the first distortionaccording to the image projection direction being changed.

In the projecting of an image, the image may start to be projected at atiming when the moving table enters the inside of the bore of thehousing, or when a head of an object enters the inside of the bore ofthe housing.

A first arrangement, in which the head of the object faces a directionin which the moving table enters the inside of the bore of the housing,and a second arrangement, in which legs of the object face the directionin which the moving table enters the inside of the bore of the housing,have different timings when the beam projector starts to project animage. For example, in the first arrangement, the beam projector maystart to project the image onto the inner wall of the housing at atiming when the head of the object enters the inside of the bore of thehousing, and in the second arrangement, the beam projector may start toproject the image onto the inner wall of the housing at a timing when aneck of the object enters the inside of the bore of the housing.

The method may further include changing the image projection directionof the beam projector according to a posture or looking direction of anobject onto which an image is to be projected.

The beam projector may include an luminance sensor, and beam brightnessof the beam projector may be controlled according to an internalluminance state of the bore.

The disposing of a beam projector may include disposing the beamprojector on the moving table, wherein an image may be displayed in thebore of the MRI apparatus, in which the beam projector is disposed inthe bore of the housing, when the moving table enters an inside of thebore of the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects will become more apparent by describingin detail certain exemplary embodiments, with reference to theaccompanying drawings, in which:

FIG. 1 illustrates a schematic configuration of an MRI apparatusaccording to an exemplary embodiment;

FIG. 2 illustrates a block diagram of a display apparatus in a bore ofthe MRI apparatus of FIG. 1;

FIG. 3 illustrates a block diagram of a beam projector of the MRIapparatus of FIG. 1;

FIG. 4 illustrates an example of a driving circuit of a light sourcedriver in the beam projector of FIG. 3;

FIG. 5 is a diagram for describing a relationship between a magneticfield in the bore and a coil arrangement of the beam projector in theMRI apparatus of FIG. 1;

FIG. 6 shows an example in which the light source driver of FIG. 4applies power to R, G, and B light sources;

FIGS. 7, 8, and 9 illustrate an operation of the MRI apparatus of FIG.1;

FIG. 10 illustrates a schematic configuration of an MRI apparatusaccording to another exemplary embodiment;

FIG. 11 illustrates a schematic configuration of a detachable moduleapplied to the MRI apparatus of FIG. 10;

FIG. 12 illustrates an operation of the MRI apparatus of FIG. 10; and

FIG. 13 illustrates a schematic configuration of an MRI apparatusaccording to another exemplary embodiment.

DETAILED DESCRIPTION

Certain exemplary embodiments are described in greater detail below withreference to the accompanying drawings.

In the following description, same reference numerals are used for thesame elements even in different drawings. The matters defined in thedescription, such as detailed construction and elements, are provided toassist in a comprehensive understanding of exemplary embodiments. Thus,it is apparent that exemplary embodiments can be carried out withoutthose specifically defined matters. Also, functions or elements known inthe related art are not described in detail since they would obscure theexemplary embodiments with unnecessary detail.

In the description, when a part “includes” or “comprises” an element,unless there is a particular description contrary thereto, the part canfurther include other elements, not excluding the other elements. Also,the term ‘unit’ in the exemplary embodiments means a software componentor hardware components such as a field-programmable gate array (FPGA) oran application-specific integrated circuit (ASIC), and performs aspecific function. However, the term ‘unit’ is not limited to softwareor hardware. The ‘unit’ may be formed so as to be in a addressablestorage medium, or may be formed so as to operate one or moreprocessors. Thus, for example, the term ‘unit’ may refer to componentssuch as software components, object-oriented software components, classcomponents, and task components, and may include processes, functions,attributes, procedures, subroutines, segments of program code, drivers,firmware, micro codes, circuits, data, a database, data structures,tables, arrays, or variables. A function provided by the components and‘units’ may be associated with the smaller number of components and‘units’, or may be divided into additional components and ‘units’.

Throughout the specification, a “user” may be, but is not limited to, amedical expert including a doctor, a nurse, a medical laboratorytechnologist, a medial image expert, and a technician who repairs amedical apparatus.

FIG. 1 illustrates a schematic configuration of an MRI apparatus 100according to an exemplary embodiment, and FIG. 2 illustrates a blockdiagram of a display apparatus in a bore of the MRI apparatus 100 ofFIG. 1. FIG. 3 illustrates a block diagram of a beam projector 160 ofthe MRI apparatus 100 of FIG. 1, and FIG. 4 illustrates an example of adriving circuit of a light source driver in the beam projector 160 ofFIG. 3.

Referring to FIGS. 1 and 2, the MRI apparatus 100 according to thepresent exemplary embodiment includes a magnetic assembly 96 disposed ina housing 110, which applies a magnetic field for an MR image to theinside of a housing 110, and an MRI controller 180 that applies power tothe magnetic assembly and controls the magnetic assembly. The MRIapparatus 100 enables a user to manipulate the MRI controller 180 byusing a console 190 which is provided outside the MRI apparatus 100, andthe console 190 displays an image generated by the MRI apparatus 100.

The housing 110 has a cylindrical structure including a bore 98, and atable 120 with an object located thereon is moved into the bore. Here,the cylindrical structure denotes a case, in which the bore of thehousing 110 is wholly cylindrical, or a case in which the bore of thehousing 110 is partially cylindrical. Reference numeral 110 a refers toan inner wall 110 a configuring the bore of the housing 110. Asdescribed below, the inner wall 110 a of the housing 110 acts as ascreen for the beam projector 160.

The magnetic assembly is accommodated in the housing 110 having acylindrical structure, and includes a main magnet and a gradient coil.The main magnet generates a main magnetic field (B₀ of FIG. 5) thatmagnetizes a chemical element (i.e., an atomic nucleus such as hydrogen,phosphorous, or natrium) causing an MR phenomenon among chemicalelements distributed in a human body. The main magnet may be asuperconductive magnet or a permanent magnet. For example, thesuperconductive magnet may be used to generate a magnetic field of 0.5 Tor more. The main magnet may be provided to have a cylindrical structurecorresponding to the cylindrical structure of the housing 110, and themain magnetic field B₀ generated by the main magnet may have a directionparallel to a center axis of the bore. The gradient coil generates aspatially linear gradient magnetic field for capturing an MR image.Generally, three gradient coils which respectively generate gradientmagnetic fields in an x-direction, a y-direction, and a z-direction areused for an MR image. When a magnetization vector is rotating on ahorizontal plane, the gradient coil spatially controls a rotationfrequency or a phase of the magnetization vector in order for an MRimage signal to be expressed in a spatial frequency domain, namely, ak-domain. The MRI apparatus 100 according to the present exemplaryembodiment includes an RF coil that is used to apply an electromagneticwave to a human body for resonating an internal magnetization vector ofthe human body, and to receive an MR signal. The RF coil may be providedat an inner surface of the gradient coil, and may configure a portion ofa cylindrical magnetic structure along with the main magnet and thegradient coil. Alternatively, the RF coil may be provided as a separatemodule in the bore of the housing 110. The magnetic assembly forgenerating an MR image is known to one of ordinary skill in the art.

The table 120 includes a moving table 121 that moves to inside thehousing 110 in a state where an object lies on the table 120, a support122 that supports the moving table 121, and a table driver 125 thatdrives the moving table 121 in a direction of an arrow 126 or 128according to control by the MRI controller 180.

A display apparatus provided in the bore is configured with the beamprojector 160 that projects an image onto the bore of the housing 110,and at least one of a first detachable module 150-1 and a seconddetachable module 150-2 that is detachably attached to the beamprojector 160. The MRI controller 180 controls the beam projector 160,the first detachable module 150-1 and the second detachable module150-2.

The first detachable module 150-1 and the second detachable module 150-2are provided on the moving table 121, and the beam projector 160 isdetachably attached thereto. A coupling part between the first andsecond detachable modules 150-1,150-2 and the beam projector 160 may usea connector or a docking method which is known to one of ordinary skillin the art.

One of the first detachable module 150-1 and the second detachablemodule 150-2 may be disposed adjacent to a position at which a head ofan object lying for imaging is located. The head position of the objectmay be changed according to an imaging purpose. Thus, the first andsecond detachable modules 150-1 and 150-2 may be respectively disposedat positions adjacent to both ends in a length direction of the movingtable 121. The first and second detachable modules 150-1 and 150-2 mayinclude the same elements. The beam projector 160 may be detachablyattached to each of the first and second detachable modules 150-1 and150-2. In addition, each of the first and second detachable modules150-1 and 150-2 may act as a connector that transfers power, a videosignal, and a control signal (which are supplied from the MRI controller180 provided outside the housing 110) to the beam projector 160.Furthermore, each of the first and second detachable modules 150-1 and150-2 may include a detachable sensor (not shown) for detectingattachment/detachment of the beam projector 160, and transferinformation, for example, attachment/detachment information, about thepresence of attachment of the beam projector 160 to the MRI controller180.

The MRI controller 180 processes the control signal, which controls thefirst detachable module 150-1, the second detachable module 150-2 andthe beam projector 160, and the video signal supplied to the beamprojector 160. Also, the MRI controller 180 may control various elementsof the MRI apparatus 100, and process an MR image. As described below,the video signal supplied to the beam projector 160 may be relevant tovarious contents that mitigate a tension of an object during an imagingtime and provide useful information. The contents may include, forexample, a moving image, a photograph, imaging state information(imaging time information, imaging guide information, and imaging partinformation), and function MRI (FRMI) information. When the detachablesensor for detecting attachment/detachment of the beam projector 160 isprovided at each of the first and second detachable modules 150-1 and150-2, the MRI controller 180 may selectively supply the video signal,the control signal, and projector power to one of the first and seconddetachable modules 150-1 and 150-2 to which the beam projector isattached.

The beam projector 160 is an element that projects an image. The beamprojector 160 may be selectively attached (i.e., docked) to one of thefirst and second detachable modules 150-1 and 150-2. When the movingtable 121 is inserted into the bore of the housing 110 with the beamprojector 160 being attached to one of the first and second detachablemodules 150-1 and 150-2, the beam projector 160 projects an optical beamof an image onto the inner wall 110 a configuring the bore. That is, theinner wall 110 a of the housing 110 acts as a screen for the beamprojector 160.

FIG. 3 illustrates a block diagram of the beam projector 160. Referringto FIGS. 2 and 3, the beam projector 160 includes a video signalreceiver 161, a central processing unit (CPU) 162, a beam projectioncontroller 165, a light source driver 166, a light source 167, an imagepanel 169, a projection lens 170, and an illumination lens 171. When thevideo signal transferred from the MRI controller 180 is input, the videosignal receiver 161 transfers the video signal to the beam projectioncontroller 165. The transferred video signal is converted into an imagesignal for beam projection by the beam projection controller 165, andthe image signal is transferred to the image panel 169. The image panel169 may use, for example, a known image panel such as a transmissiveliquid crystal display (LCD) panel, a reflective DMD panel, or the like.The beam projection controller 165 transfers a light source drivingsignal corresponding to the image signal for beam projection to thelight source driver 166. The CPU 162 that controls the video signalreceiver 161 or the light source driver 166 may be provided with thecontrol signal input to the beam projector 160 and control data storedin a memory 163. Also, a power converter 164 that converts power to alevel suitable for various elements of the beam projector 160 may bebuilt into the beam projector 160. The image panel 169 displays an imageaccording to the image signal for beam projection, and when the lightsource 167 is driven according to the transferred light source drivingsignal, an optical beam irradiated on the image panel 169 through theillumination lens 171 passes through the image panel 169 or is reflectedby the image panel 169, and thus is modulated according to an imagedisplayed by the image panel 169 and is projected through the projectionlens 170. The light source 167 may use, for example, a light emittingdiode (LED), a lamp, or any other appropriate light source.

The projection lens 170 automatically or manually controls a focus inorder for an optical beam of a projected image to be image-formed at aninner wall of the housing 110.

In order to display the projected image in color, for example, the lightsource 167 may include a red (R) light source, a green (G) light source,and a blue (B) light source, which may be sequentially driven. The MRIcontroller 180 supplies the video signal corresponding to a color image.The beam projection controller 165 decomposes the color imagecorresponding to one frame into a red image, a green image, and a blueimage, and sequentially transfers the red image, the green image, andthe blue image to the image panel 169 in synchronization with sequentialdriving of the red light source, green light source, and blue lightsource of the light source 167. Therefore, an image projected by thebeam projector 160 may be displayed in color. The light source 167 mayinclude a single-color light source in addition to the red light source,the green light source, and the blue light source.

The beam projector 160 may further include a luminance sensor 168 thatsenses an internal luminance of the bore of the housing 110. Theinternal luminance information of the bore sensed by the luminancesensor 168 may be transferred to the light source driver 166, and may beused to adjust brightness in driving the light source 167. Also,brightness may be changed according to a depth of the bore of thehousing 110. Therefore, in response to a depth to which the moving table121 moves into the housing 110, brightness of the light source 167 maybe controlled to be suitable for the depth. That is, as a position of animage formed at the inner wall 110 a of the housing 110 is moved, alight amount of an image projected onto the beam projector 160 ischanged, and thus, the projected image maintains constant brightness.

Since heat is generated by the light source 167 while the beam projector160 is being driven, an object is sensitive to the heat generated fromthe beam projector 160. Therefore, the beam projector 160 is disposed tobe separated from a head of the object by a certain gap. The beamprojector 160 may further include a heat dissipating member (not shown).The heat dissipating member may use a known element such as a heat sink,a heat dissipating fan, or the like. When an electromagnetic motor isused for driving the heat dissipating fan, an electromagnetic shield maybe used in consideration of an internal high magnetic field of the boreof the housing 110.

Since an image for projection has various resolutions and a screen size,the beam projection controller 165 may perform scaling signal processingthat converts the input video signal so as to match a format (forexample, a resolution, a screen size, etc.) for beam projection. When auser manipulates the console 190 to select an image to be projected, animage output change request is transferred to the beam projector 160through the MRI controller 180, and the beam projection controller 165may operate according to the image output change request. Such a scalermay be provided in the MRI controller 180.

The beam projector 160 is inserted into the bore of the housing 110along with the moving table 121, and thus may include an electromagneticshield such that an internal magnetic field and electric field of thebore of the housing 110 is not affected by the beam projector 160 ordoes not affect the beam projector 160.

Moreover, the beam projector 160 may have a circuit configuration thatminimizes an influence of the internal high magnetic field of the borein the housing 110.

The inventor found a problem in which when the beam projector 160 isdisposed in the bore of the MRI apparatus 100, noise of an audiblefrequency band occurs. Therefore, the inventor found that the noise ofthe audible frequency band is removed by adjusting a coil among theelements of the beam projector 160 such that a direction of a magneticfield, which is generated by the coil according to a current beingapplied to the coil, is parallel to a direction of the main magneticfield (B₀ of FIG. 5) which is applied for capturing an MR image in thebore.

The coil, for example, may be applied to the light source driver 166 ofthe beam projector 160. Hereinafter, a case in which the coil is appliedto the light source driver 166 will be described as an example.

FIG. 4 illustrates a portion of a driving circuit in the light sourcedriver 166 which is a portion of a circuit block of the beam projector160.

The light source driver 166 may increase or decrease a voltage suppliedto the beam projector 160. Also, a power source for a light sourcesupplies a constant voltage even when a current is rapidly changed, formaintaining constant brightness of the light source 167 when the beamprojector 160 operates. In the following description of the light sourcedriver 166, an LED is used as the light source 167 as an example.

Referring to FIG. 4, the light source driver 166 according to thepresent exemplary embodiment may include a direct current (DC) converter1661. The DC converter 1661 may be a DC-DC converter that converts aninput DC voltage into a predetermined voltage. Voltage conversion by theDC converter 1661 may be performed, for example, by adjusting a ratio ofan on time and an off time through pulse width modulation. In thevoltage conversion, a current flowing in a circuit is rapidly changedeach time switching between on and off is performed. Therefore, the DCconverter 1661 may use a coil type inductor 1662 for responding to afast switching operation.

The inductor 1662 may have a cylindrical air-core coil structure. Acylindrical air-core coil has a structure in which a wire is wound in acylindrical shape of which the inside is empty or is supported by anonmagnetic material (for example, Bakelite). A magnetic core, such asiron or ferrite which is directly provided with magnetic force from amagnetic field, is not applied to the inductor 1662, thereby minimizingan influence of a stronger magnetic field generated in the bore of thehousing 110.

Moreover, as illustrated in FIG. 5, a cylindrical coil configuring theinductor 1662 is disposed such that a central axis of the cylindricalcoil is parallel to a direction of the main magnetic field B₀ generatedby the main magnet of the MRI apparatus 100. When a current is appliedto the cylindrical coil, a magnetic field is generated inside thecylindrical coil in a direction parallel to the central axis of thecylindrical coil. Therefore, as illustrated in FIG. 5, the cylindricalcoil configuring the inductor 1662 is disposed such that the centralaxis of the cylindrical coil is parallel to the direction of the mainmagnetic field B₀, and thus, a direction of a magnetic field(hereinafter referred to as an inductor magnetic field) generated when acurrent flows in the coil itself of the inductor 1662 may be parallel tothe direction of the main magnetic field B₀. As described above, themain magnetic field B₀ generated by the main magnet may have a directionparallel to the center axis of the bore of the housing 110, and thus,the center axis of the inductor 1662 may have a direction parallel tothe center axis of the housing 110.

Next, an operation of the light source driver 166 and an influence ofthe main magnetic field B₀ generated by the main magnet will bedescribed in detail with reference to FIGS. 4 to 6.

Referring to FIG. 4, power output from the DC converter 1661 is suppliedto the red light source, green light source, and blue light source ofthe light source 167. The light source driver 166 respectively appliesred, green, and blue enable signals R_ENABLE, G_ENABLE and B_ENABLE to aplurality of switching elements 1665 (which are respectively connectedto the red light source, green light source, and blue light source ofthe light source 167) according to a light source driving signaltransferred from the beam projection controller 165. Thus, the red lightsource, green light source, and blue light source of the light source167 may be sequentially driven. FIG. 6 shows examples of driving signalsrespectively applied to the red light source, the green light source,and the blue light source. As shown in FIG. 6, for example, a drivingsignal for the red light source is a pulse wave of 1.4 ms, whichcorresponds to an audible frequency band of 833 Hz. A driving currentfor the green and blue light sources is a pulse wave of 3.25 ms, whichcorresponds to an audible frequency band of 397.7 Hz.

As described above, when the beam projector 160 is located in the bore,the inductor 1662 of the beam projector 160 may be provided with forceobtained by an electromagnetic interaction with the main magnetic fieldB₀ generated in the bore. That is, when the driving current supplied tothe red light source, green light source, and blue light source of thelight source 167 flows in a circuit of the light source driver 166,force is applied to a wire configuring the coil of the inductor 1662according to Fleming's left-hand rule. Here, the force is periodicallyapplied to the wire at the above-described audible frequency band.

If the central axis of the cylindrical coil configuring the inductor1662 is inclined with respect to the direction of the main magneticfield B₀ generated by the main magnet, force acting on the wireconfiguring the coil of the inductor 1662 acts like F2 illustrated inFIG. 5, and thus, a balance of force is broken, causing the inductor1662 having the cylindrical coil type to vibrate (i.e., noise) at theaudible frequency band. Introduction of the beam projector 160 providesvarious contents (for example, a moving image, a photograph, imagingstate information (imaging time information, imaging guide information,and imaging part information), and FRMI information) to an object forwhom an MR image is being captured, thereby giving the object apsychologically stable feeling. However, when noise of the audiblefrequency band occurs, an adverse effect is applied to an examinationenvironment of the object.

In the MRI apparatus 100 according to the present exemplary embodiment,as described above, the arrangement direction of the inductor 1662 isset such that the direction of the inductor magnetic field, which isgenerated with a current flowing in the inductor 1662, is parallel tothe direction of the main magnetic field B₀ generated by the mainmagnet, namely, the central axis of the cylindrical coil configuring theinductor 1662 is disposed to be parallel to the direction of the mainmagnetic B₀ generated by the main magnet, and thus, force acting on thewire configuring the coil of the inductor 1662 symmetrically acts likeF1 illustrated in FIG. 5 to counteract vibration. Accordingly, the MRIapparatus 100 according to the present exemplary embodiment providesvarious contents to an object in a state where noise does not occur inthe beam projector 160.

In the present exemplary embodiment, the detailed configuration of thelight source driver 166 is only an example, but is not limited thereto.Since various driving circuits using a coil are known, as describedabove, the coil applied to the various driving circuits is also disposedsuch that a magnetic field, which is generated by the coil when acurrent is applied to the coil, is parallel to the direction of the mainmagnetic field in the bore, thereby preventing noise from occurring inthe coil.

Moreover, in the present exemplary embodiment, the inductor 1662 of thelight source driver 166 is described as an example of the coil appliedto the beam projector 160, but is not limited thereto. A coil may beapplied to the other element of the beam projector 160, in addition tothe light source driver 166. For example, a coil may be applied to thepower converter 164 among the elements of the beam projector 160. Inthis case, as described above, the coil may be disposed such that amagnetic field, which is generated by the coil when a current is appliedto the coil, is parallel to the direction of the main magnetic field inthe bore, thereby preventing noise from occurring in the coil.

Next, an operation of the MRI apparatus 100 according to an exemplaryembodiment will be described in detail with reference to FIGS. 7 to 9.

FIGS. 7 and 8 illustrate an operation in which with an object lying onthe moving table 121, the object is moved (direction arrow 126) in thebore of the housing 110. Referring to FIGS. 7 and 8, capturing of an MRimage is performed with the object lying on the moving table 121.Therefore, before the MR image starts to be captured, the beam projector160 is mounted on one of the first and second detachable modules 150-1and 150-2 which is adjacent to a head of the object. FIGS. 7 and 8exemplarily illustrate a case in which the first detachable module 150-1is adjacent to the head of the object.

When the MR image starts to be captured, the moving table 121 enters theinside of the bore of the housing 110. When the moving table 121 entersthe inside of the bore of the housing 110, the beam projector 160 isdriven to project an image onto the inner wall 110 a of the housing 110.A timing when the beam projector 160 starts to project the image may bea timing, when the head of the object enters the bore of the housing110, or a timing immediately before or after the timing. Alternatively,the timing when the beam projector 160 starts to project the image maybe set to a timing when the moving table 121 enters the inside of thebore of the housing 110, regardless of a head position of the object.

The beam projector 160 projects an image onto the inner wall 110 a ofthe housing 110 which is disposed at a position facing eyes of theobject. When it is requested that the eyes of the object are fixed to astate of looking at an upper side while capturing an image, the beamprojector 160 may projector an image onto the inner wall 110 a of thehousing 110 which is disposed over the head of the object.

When the beam projector 160 is disposed adjacent to the head of theobject, an image of the beam projector may be projected with a viewingangle of the object being ensured. Also, when the beam projector 160 isdisposed on the moving table 121, the moving table 121 is moved(direction arrow 126), and simultaneously the image 200 projected by thebeam projector 160 is also moved (direction arrow 127). Therefore, theimage is moved along with the movement of the moving table 121 while animage of the object is being captured, and thus, the object looks at theimage without moving the eyes.

A projected image may be, for example, content such as a moving image, aphotograph, imaging state information (imaging time information, imagingguide information, and imaging part information), or FRMI information).For example, when an MR image starts to be captured, schematic imagingguide information may be displayed. Also, an imaging end time may bedisplayed in real time. In addition, an image including content such asa news irrelevant to imaging may be displayed for mitigating a tensionof the object.

A direction facing the head of the object may be reversely changed withrespect to a length direction of the moving table 120 according to animaging purpose. Referring to FIG. 9, the direction facing the head ofthe object is opposite to a direction illustrated in FIGS. 7 and 8. Whena position of the object is reversely changed, the beam projector 160 isdetached from the first detachable module 150-1, and is attached to thesecond detachable module 150-2 adjacent to the head of the object ofwhich a lying position has been reversely changed. That is, in FIGS. 7and 8, since the head of the object is disposed adjacent to the firstdetachable module 150-1, the beam projector 160 operates in a state ofbeing attached to the first detachable module 150-1. On the other hand,in FIG. 9, since the head of the object is changed to be adjacent to thesecond detachable module 150-2, the beam projector 160 is detached fromthe first detachable module 150-1, and is attached to the seconddetachable module 150-2. As described above, the detachable sensor isincluded in each of the first and second detachable modules 150-1 and150-2, and detects attachment/detachment. When information aboutattachment/detachment of the beam projector 160 is transferred, the MRIcontroller 180 stops the supply of the video signal and/or controlsignal and power to the first detachable module 150-1 from which thebeam projector 160 is detached, and starts the supply of the videosignal and/or control signal and power to the second detachable module150-2 from which the beam projector 160 is attached detached.

A first arrangement (see FIGS. 7 and 8), in which the head of the objectfaces a direction in which the moving table 121 enters the inside of thebore of the housing 110, and a second arrangement (see FIG. 9), in whichlegs of the object face the direction in which the moving table 121enters the inside of the bore of the housing 110, have different timingswhen the beam projector 160 starts to project an image. That is, in thefirst arrangement, the beam projector 160 starts to project the imageonto the inner wall 110 a of the housing 110 at a timing when the headof the object enters the inside of the bore of the housing 110, and inthe second arrangement, the beam projector 160 starts to project theimage onto the inner wall 110 a of the housing 110 at a timing when aneck of the object enters the inside of the bore of the housing 110.However, a timing when the beam projector 160 projects the image may bechanged by selection of the user.

When the user selects appropriate content by using the console 190,information of the selected content is transferred to the beam projector160 through the MRI controller 180 and at least one of the first andsecond detachable modules 150-1, 150-2, and the CPU 162 which receives arequest for an image output of the beam projector 160 controls theelements of the beam projector 160 in order for the beam projector 160to project the image. When the selected content does not match aresolution and a screen size which are appropriate for image output, theMRI controller 180 may transfer a control command requiring the changingof image output to the beam projector 160, and the beam projectioncontroller 165 of the beam projector 160 may perform down/up scaling ofthe selected content so as to match the resolution and the screen size,which are appropriate for image output, according to the image outputchange request.

As described above, since the MRI apparatus 100 according to anexemplary embodiment displays an image in an internal space of the borein a beam projection scheme to provide various contents to an object,the MRI apparatus 100 mitigates boredom or inconvenience of the objectcaused by long-time imaging, and thus decreases a movement of theobject, thereby preventing a quality of a captured image from beingdegraded.

FIG. 10 illustrates a schematic configuration of an MRI apparatus 100′according to another exemplary embodiment. FIG. 11 illustrates aschematic configuration of a detachable module 150′ applied to the MRIapparatus 100′ of FIG. 10. Except the detachable module 150′, the MRIapparatus 100′ according to the present exemplary embodimentsubstantially includes the same elements as those of the MRI apparatus100 described above and repeated descriptions are omitted.

Referring to FIGS. 10 and 11, the detachable module 150′ according tothe present exemplary embodiment may include first and second detachablemodules 150′-1 and 150′-2 that are respectively disposed at positionsadjacent to both ends in a length direction of the moving table 121. Thefirst and second detachable modules 150′-1 and 150′-2 may include thesame elements. In the following description, the detachable module 150′may refer to one of the first and second detachable modules 150′-1 and150′-2.

The detachable module 150′ may include a base material 1501, which isfixed onto the moving table 121, and a rotation unit 1502 that isprovided at the base material 1501. The rotation unit 1502 may include,for example, a first rotation unit 1503 that rotates in one of firstdirections as indicated by a reference numeral 1503A and a secondrotation unit 1504 that rotates in one of second directions as indicatedby a reference numeral 1504A. The first and second directions 1503A and1504A may be different directions, and thus, a rest 1505 may face anarbitrary direction by a combination of the first and second directions1503A and 1504A. For example, the first direction 1503A of the firstrotation unit 1503 may be a rotation direction which has a normal-linedirection of the base material 1501 as a rotation axis, and the seconddirection 1504A may be a rotation direction which has, as a rotationaxis, a direction vertical to the rotation axis of the first direction1503A.

The detachable module 150′ may further include a driving motor 1508 thatrotates the rotation unit 1502. The driving motor 1508 is controlled bythe MRI controller 180. A driving shaft 1507, which transfers drivingforce between the rotation unit 1502 and the driving motor 1508, may behard or flexible. When the rotation unit 1502 is configured with thefirst and second rotation units 1503 and 1504, the driving forcetransferred through the driving shaft 1507 may be selectivelydistributed to the first and second rotation units 1503 and 1504. Thedriving motor 1508 may be disposed outside the housing 110 withoutentering the bore of the housing 110, and may provide the driving forceto the rotation unit 1502 through the driving shaft 1507. When thedriving motor 1508 is disposed outside the housing 110, despite anelectromagnetic motor being used as the driving motor 1508, aninteraction with the internal magnetic field of the bore of the housing110 is minimized, thereby reducing a burden of the electromagneticshield.

The rest 1505, in which the beam projector 160 is detachably provided,is provided at the rotation unit 1502. A connector 1506, whichestablishes an electrical and mechanical connection with the connector1601 of the beam projector 160, is provided at the rest 1505. Aplurality of electrode terminals, which transfer the video signal andthe control signal from the MRI controller 180 to the beam projector160, are provided at the connector 1506 of the rest 1505. The videosignal, the control signal, and power may be transferred from thedetachable module 150′ to the beam projector 160 through a mutualconnection between the connector 1506 of the detachable module 150′ anda connector terminal 1601 of the beam projector 160.

Rotation of the rotation unit 1502 changes a direction of the rest 1505with the beam projector 160 mounted thereon, and thus, an imageprojection direction of the beam projector 160 may be changed tocorrespond to a looking direction of the an object.

A motor driver (not shown) for driving the driving motor 1506 may beadditionally provided at the detachable module 150′. The motor drivermay receive motor power and a control signal, which are used to drivethe driving motor 1506, from the MRI controller 180 to drive the drivingmotor 1506, thereby changing the image projection direction of the beamprojector 160.

FIG. 12 illustrates an operation of the MRI apparatus 100′ of FIG. 10.

A direction, in which an object lies on the moving table 120, may bechanged according to an imaging purpose. For example, as illustrated inFIG. 12, the object may lie on its side for the purpose of capturing animage. In this case, eyes of the object face a side direction, and thus,the detachable module 150′ (the first detachable modules 150′-1 or thesecond detachable modules 150′-2 in FIG. 11) with the beam projector 160mounted thereon may rotate (arrow C) the rotation unit 1502 in order forthe image projection direction of the beam projector 160 to face theside direction substantially coinciding with a looking direction of theobject.

The image projection direction of the beam projector 160 may be changedautomatically or by manual manipulation of a user. For example, when theobject lies on its side, the user may manipulate the console 190 inorder for the image projection direction of the beam projector 160 toface the side direction, in response to a movement of the object.

The MRI apparatus 100′ may further include a position tracing sensor140, as shown in FIG. 10, that detects a lying position of the object ora direction which eyes of the object face. The position tracing sensor140 may be a camera, which photographs a face of the object, or theother known sensor. For example, when the position tracing sensor 140 isthe camera, a face photograph of the object is transferred to the MRIcontroller 180, and a signal processor 185 of the MRI controller 180detects an eyeball position of the object from the face photograph ofthe object. A method, which detects the eyeball position from the facephotograph, is known to those skilled in the art, and thus, its detaileddescription is not provided. The MRI controller 180 may automaticallyrotate (arrow C) the rotation unit 1502 of the detachable module 150′ inorder for the image projection direction of the beam projector 160 toface a direction substantially coinciding with the looking direction ofthe object, in response to the detected eyeball position of the object.

An exemplary embodiment described above with reference to FIGS. 10 to12, the rotation unit 1502 provided at the detachable module 150′ is anexample of a projection direction changing unit that changes aprojection direction of the beam projector 160. As another example, theprojection direction changing unit may be provided at the beam projectoritself. For example, the projection lens 170 may be mounted on a housingof the beam projector 160 so as to enable a direction of the projectionlens 170 to be changed.

Moreover, in an exemplary embodiment described above with reference toFIGS. 10 to 12, a driving module configured with the driving shaft 1507and the driving motor 1508 is described as an example, but the otherknown driving scheme may be applied. For example, a hydraulic system maybe applied as the driving module for the rotation unit 1502 of thedetachable module 150′. Furthermore, the rotation unit 1502 may bemanually rotated.

Moreover, in an exemplary embodiment described above with reference toFIGS. 10 to 12, a configuration in which the first and second rotationunits 1503 and 1504 of the detachable module 150′ change a direction ofthe rest 1505 through a combination of lateral rotation and verticalrotation is described as an example, but single-axis rotation ormulti-axis rotation may be applied to the rotation unit of thedetachable module 150′. Furthermore, a coupling position in which thebeam projector 160 is coupled or docked to the detachable module 150′may be provided as a plurality of positions including an upper side, aleft side, and a right side of the detachable module 150′, and thus, theimage projection direction of the beam projector 160 may be changed byselectively changing the position in which the beam projector 160 iscoupled to the detachable module 150′.

An image projected onto the inner wall 110 a may be distorted due to acurved shape of the inner wall 110 a, especially when the imageprojection is moved along a circumference of the inner wall 110 a. Also,an optical beam may be projected askew with respect to the inner wall110 a due to gradient projection and an amount of a skew distortion mayvary when the image projection direction is moved in a verticaldirection of the housing 110. Therefore, the beam projection controller165 or the MRI controller 180 causes a primary pre-distortion whichcounteracts the curved-surface distortion or the skew distortion in animage signal processing operation, thereby removing the curved-surfacedistortion of an image formed on the curved inner wall 110 a.

In the above-described exemplary embodiments, the first and seconddetachable modules 150-1 and 150-2 (or 150′-1 and 150′-2) are describedas an example, but a number of the detachable modules of an exemplaryembodiment is not limited thereto. For example, a number of thedetachable modules may be one, three, etc., and the detachable modulesmay be provided at one, three or more positions on the moving table 121.Furthermore, the beam projector 160 may be fixed to and disposed on themoving table 121 without using any of the detachable modules.

Moreover, in the above-described exemplary embodiments, the bore isdescribed to be cylindrical, as an example, but an exemplary embodimentis not limited thereto. For example, the bore of the housing 110 mayhave an oval shape, or have the other shape.

FIG. 13 illustrates a schematic configuration of an MRI apparatus 100″according to another exemplary embodiment. Referring to FIG. 13, a boreof a housing 111 of the MRI apparatus 100″ may include a curved innerwall 111 a and a planar inner wall 111 b. The planar inner wall 111 bmay be disposed on the bore of the housing 111. The planar inner wall111 b may be formed to extend in a length direction of the bore of thehousing 111. Except a structure of the bore of the housing 111, the MRIapparatus 100″ according to the present exemplary embodimentsubstantially includes the same elements as those of the MRI apparatuses100 and 100′ described above and repeated descriptions are omitted.

The beam projector 160 may project an image onto the planar inner wall111 b. A flat plate may be disposed at an upper portion corresponding toa direction in which eyes of an object face in a state of lying supinelyon the moving table 121. The object may look at the image projected bythe beam projector 160 in a state of lying supinely on the moving table121. When the image is projected onto the planar inner wall 111 b,curved-surface distortion does not occur in the projected image, andthus, correction for the curved-surface distortion may be omitted fromthe signal processing operation described above.

In the present exemplary embodiment, a case in which the planar innerwall 111 b is disposed in the top of the bore of the housing 111 isdescribed as an example, but an exemplary embodiment is not limitedthereto. For example, the planar inner wall 111 b may be disposed at aside of the bore of the housing 111.

Furthermore, in the present exemplary embodiment, a case in which onlyone planar inner wall 111 b is provided is described as an example, butan exemplary embodiment is not limited thereto. That is, the bore of thehousing 111 may be configured by a combination of a plurality of planarinner walls and a curved inner wall, or may be configured with only theplurality of planar inner walls. For example, all inner wallsconfiguring the bore of the housing 111 may be planar inner walls, and ahorizontal cross-sectional surface of the bore may have a polygonalshape.

As described above, in the MRI apparatus according to the exemplaryembodiments, since the beam projector is disposed in the bore, variouscontents are provided to an object being imaged. In addition, the coilof the beam projector is disposed in consideration of a direction of amagnetic field, and thus, even when the light source driver using aninductor having a coil structure is applied, occurrence of noise isprevented, thereby enabling an MR image of an object to be captured in acomfortable state.

The foregoing exemplary embodiments and advantages are merely exemplaryand are not to be construed as limiting. The exemplary embodiments canbe readily applied to other types of apparatuses. Also, the descriptionof the exemplary embodiments is intended to be illustrative, and not tolimit the scope of the claims, and many alternatives, modifications, andvariations will be apparent to those skilled in the art.

What is claimed is:
 1. A magnetic resonance imaging (MRI) apparatuscomprising: a housing that includes a bore; a table which is configuredto be moved into the bore; and a beam projector that is configured to bedisposed on the table, and to project an image into the bore, whereinthe beam projector includes a coil, and the coil is configured to bedisposed so that a central axis of the coil is parallel to a center axisof the bore.
 2. The MRI apparatus of claim 1, wherein the coil comprisesan air-core coil.
 3. The MRI apparatus of claim 1, wherein the coil is acylindrical coil.
 4. The MRI apparatus of claim 1, wherein the coil is acylindrical air-core coil.
 5. The MRI apparatus of claim 1, wherein thebeam projector comprises: an image panel configured to display theimage; a light source configured to emit light onto the image panel; alight source driver configured to supply a power to the light source;and a projection lens configured to project the image displayed by theimage panel, wherein the coil comprises an inductor provided at thelight source driver.
 6. The MRI apparatus of claim 5, wherein the lightsource driver comprises a DC converter that converts an input DC voltageinto a DC voltage of at least one another level.
 7. The MRI apparatus ofclaim 5, wherein the light source comprises red, green, and blue (RGB)light sources, and the light source driver sequentially supplies acurrent to the RGB light sources.
 8. The MRI apparatus of claim 1,wherein an image-forming position, in which the image projected from thebeam projector is formed inside the bore of the housing, is movedaccording to a position to which the table is moved in the bore.
 9. TheMRI apparatus of claim 1, wherein the beam projector is disposed near atleast one of a first end and a second end of the table, in a lengthdirection of the table.
 10. The MRI apparatus of claim 1, furthercomprising a detachable module configured to be disposed on the tableand to be detachably attached to the beam projector.
 11. The MRIapparatus of claim 1, wherein the beam projector comprises a luminancesensor configured to detect a brightness level inside the bore, and theMRI apparatus further comprises a controller configured to control abeam brightness of the beam projector according to the detectedbrightness level in the bore.
 12. The MRI apparatus of claim 1, whereinthe projected image comprises at least one of an MR image beingcaptured, an MR imaging information, and a video content.
 13. The MRIapparatus of claim 1, further comprising a controller configured tocontrol the beam projector, and transfer a video signal to the beamprojector.
 14. A method of displaying an image in a bore of a magneticresonance imaging (MRI) apparatus, the method comprising: disposing abeam projector on a table which is movable; moving the table into a boreof a housing of the MRI apparatus; and projecting an image into the boreby the beam projector, wherein the beam projector includes a coil, andthe coil is configured to be disposed so that a central axis of the coilis parallel to a center axis of the bore.
 15. The method of claim 14,wherein the coil is an air-core coil.
 16. The method of claim 14,wherein the coil is a cylindrical coil.
 17. The method of claim 14,wherein the coil is a cylindrical air-core coil.
 18. The method of claim14, wherein the beam projector comprises: an image panel configured todisplay the image; a light source configured to emit light onto theimage panel; a light source driver configured to supply a power to thelight source; and a projection lens configured to project the imagedisplayed by the image panel, wherein the coil comprises an inductorprovided at the light source driver.
 19. The method of claim 14, whereinan image-forming position, in which the image projected from the beamprojector is formed inside the bore of the housing, is moved accordingto a position to which the table moves in the bore.
 20. The method ofclaim 14, wherein the beam projector is disposed in the bore when thetable enters an inside of the bore.
 21. The method of claim 14, whereinthe projected image comprises at least one of an MR image beingcaptured, an MR imaging information, and a video content.